PubMed Health⌕ Search

Biomedical subjects

C J Lyons

Publications and source records attributed to C J Lyons.

At least 19 recordsLinked to original sources
PubMed2006

Light, dark, and melatonin: emerging evidence for the importance of melatonin in ocular physiology.

Melatonin is a hormone, which is mainly produced by the pineal gland, a vestigial eye. Rather than the rods and cones, it is a newly discovered subgroup of photosensitive retinal ganglion cells, which is responsible for mediating the light-dark cycles, thus regulating melatonin's secretion. One of the correlates of the circadian rhythm of melatonin release is the habitual sleep pattern. Patients with circadian rhythm sleep disorders, including some blind patients with no light-induced suppression of melatonin, benefit from melatonin treatment. Melatonin is synthesized in the retina, lens, ciliary body as well as other parts of the body. In this review, we discuss the physiological roles of melatonin in the eye, as well as the potential therapeutic avenues currently under study.

Animals↗
PubMed2005

Argon laser photocoagulation for retinopathy of prematurity: long-term outcome.

PURPOSE: To assess the visual, refractive, ocular structural, and neurodevelopmental outcome in a group of children who were screened, treated with laser photocoagulation for threshold retinopathy of prematurity (ROP), and followed up at our institution. METHODS: The 21 survivors of a cohort of 23 children were recalled at the age of 5 years or more. They underwent a full ophthalmologic examination. A paediatric neurologist and/or developmental paediatrician performed a neurodevelopmental assessment and a neuropsychologist performed psychological testing. RESULTS: A total of 30 eyes (71.4%) had a best-corrected visual acuity (BCVA) of 20/40 or better. In all, 26 (62%) eyes were myopic; the overall mean spherical equivalent was -4.95 D. No eye had Stage 4 findings and only one eye (2.4%) progressed to stage 5 despite photocoagulation. In total, 14 patients (66.6%) showed evidence of stereopsis. Strabismus was seen in six patients (28.5%) and nystagmus in three (14.3%). Periventricular leukomalacia (PVL) was identified in five patients (23.8%), cerebral palsy (CP) in seven (33.3%), and intraventricular haemorrhage (IVH) in 13 (62%). Cerebral palsy and IVH associated strongly with visual acuity of less than 20/40 (P=0.009 and 0.047). There was also a strong association between visual acuity of 20/40 or above and a better cognitive outcome (P=0.013). CONCLUSIONS: Retinal scarring and detachment are relatively rare causes of visual morbidity 5 years or more after laser treatment for threshold ROP, but the neurological sequelae of extreme prematurity and amblyopia remain important causes of impaired visual function.

Amblyopia↗
PubMed2004

Leopard spot retinal pigmentation in infancy indicating a peroxisomal disorder.

BACKGROUND: Neonatal adrenoleucodystrophy (NALD) is a rare disorder resulting from abnormal peroxisomal biogenesis. Affected patients present in infancy with developmental delay, hypotonia, and seizures. Blindness and nystagmus are prominent features. The authors suggest a characteristic leopard spot pigmentary pattern in the peripheral retina to be diagnostic. METHODS: Three patients are reported with this presentation; the characteristic retinal appearance resulted in early diagnosis for one of these. CONCLUSION: Leopard spot retinopathy in an infant with hypotonia, seizures, developmental delay, with or without dysmorphic features and hearing impairment, is a clue to the diagnosis of NALD.

Developmental Disabilities↗
PubMed2001

Visual impairment due to a dyskinetic eye movement disorder in children with dyskinetic cerebral palsy.

Neurological lesions that cause dyskinetic cerebral palsy (CP) commonly involve ocular movements. This report describes a group of 14 children (nine males, five females) whose CP is associated with severe dyskinetic eye movements. Ages ranged from 4 months to 13 years (mean 6.9 years). Clinical features of this eye movement disorder are discussed and defined. The visual function of these children is slow, variable, and highly inefficient. They are often misdiagnosed as blind, due to cortical visual impairment. Early recognition of dyskinetic eye moment disorder and appropriate developmental and educational management are important.

Adolescent↗
PubMed2000

Cortical visual impairment in children with infantile spasms.

BACKGROUND: Infantile spasms are often associated with cortical visual impairment. METHOD: We report a series of 10 patients with infantile spasms, hypsarrhythmic electroencephalograms, and developmental delay, (ie, West syndrome), who presented with severe visual inattention despite a normal ocular examination. RESULTS: At follow-up (14 months to 6 years), 5 patients (50%) had no improvement in their visual behaviour. Although some degree of improvement was observed in the others, their visual function remained abnormal. All patients had moderate or severe mental retardation. CONCLUSIONS: The clinical features of West syndrome are reviewed, and the cause of the associated cortical visual impairment is discussed. Cortical visual impairment with infantile spasms is an important association, which pediatric ophthalmologists should recognize.

Diagnosis, Differential↗
PubMed1999

Eyelid pruritus with intravenous morphine.

The cause of eyelid pruritus (itching) may be difficult to determine, particularly in preverbal children. Tearing, photophobia, or eye rubbing may be the first manifestation of leukemic infiltration or graft-versus-host disease, necessitating early appropriate therapy. We report a child in whom persistent eye rubbing developed after bone marrow transplantation for leukemia. Morphine administration was found to be the cause of this symptom.

Analgesics, Opioid↗
PubMed1999

Acute acquired comitant esotropia: a prospective study.

PURPOSE: To define the clinical characteristics of patients presenting with acute onset esotropia and features suggestive of possible underlying central nervous system pathology. To assess the prognosis for the return of binocular function and to consider the most appropriate management. METHODS: A prospective clinical study was carried out of all patients presenting to the department of paediatric ophthalmology at a university teaching hospital over the period January 1994 to April 1997. Each patient underwent a full ophthalmological examination (including assessment of sensory status). All patients were referred to a paediatric neurologist for examination and CT and/or MRI scan. RESULTS: Ten patients presented during the study period. Uncorrected hypermetropia and/or decompensated monofixation syndrome were the commonest aetiological factors. One patient was found to have a cerebellar tumour. In 5 patients prescription of the full hypermetropic correction alone was sufficient to restore binocularity. Five patients required bilateral medial rectus recession. Binocular function was restored in all cases--in 5 cases with bifoveal fusion. CONCLUSION: Decompensation of a pre-existing phoria or monofixation syndrome appears the commonest aetiology. Prescription of the full hypermetropic correction found at cycloplegic refraction forms an essential part of initial management. No single clinical sign can reliably indicate the rare patient harbouring a tumour. A high index of suspicion should be maintained and neuro-imaging considered in the absence of expected findings such as hypermetropia or fusion potential or in the presence of atypical features or neurological signs.

Acute Disease↗
PubMed1999

Neurologic abnormalities associated with persistent hyperplastic primary vitreous.

BACKGROUND: Persistent hyperplastic primary vitreous (PHPV) is usually a unilateral ocular abnormality not associated with other systemic findings. We describe 16 patients, 7 with unilateral and 9 with bilateral PHPV, in whom significant neurologic abnormalities were identified. METHODS: The clinical records of 16 children referred to the Visually Impaired Program at a university-affiliated children's hospital in Vancouver were studied from 1970 to 1996. Further investigations, including electroencephalography, computed tomography and pediatric neurologic evaluation, were performed to ascertain neurologic deficits. RESULTS: Neurologic abnormalities were identified in three of the children with unilateral PHPV (hemiparesis, impaired coordination and homonymous hemianopia) and seven of the children with bilateral PHPV (ataxia, impaired coordination, hypotonia, spastic quadriplegia, microcephaly and deafness). INTERPRETATION: The possibility of underlying neurologic abnormality should be considered in patients with PHPV, particularly those with bilateral disease. Referral to a pediatric neurologist may be appropriate.

Abnormalities, Multiple↗
PubMed1998

Anterior segment dysgenesis and congenital glaucoma associated with partial trisomy of chromosome 1 (1q32-qter).

A child born with partial trisomy of chromosome 1 (1q32-qter) survived and was seen for anterior segment dysgenesis and congenital glaucoma. Pure trisomy 1q is rarely seen in live-born infants and has not previously been described in association with congenital glaucoma. The genetic basis for glaucoma is complicated and multifactorial and probably determined by a number of genes on a variety of chromosomes. The current case provides some evidence that part of chromosome 1 may be involved with the etiology of a glaucomatous process.

Anterior Eye Segment↗
PubMed1998

Congenital endophthalmitis following maternal shellfish ingestion.

PURPOSE: To highlight an unusual organism causing a unilateral endophthalmitis by transplacental spread. METHOD: We report a case of Plesiomonas shigelloides endophthalmitis, presenting in a newborn, with co-existing septicaemia and meningitis. There was a significant maternal history of diarrhoea associated with the ingestion of oysters 2 weeks prior to delivery. RESULT: The endophthalmitis was treated with parenteral antibiotics and topical mydriatics with complete resolution, although subsequent assessment of the affected eye suggests a poor visual outcome. CONCLUSION: Endophthalmitis in the newborn is an unusual clinical finding and usually presents with other manifestations of bacteraemia. Plesiomonas shigelloides is fortunately an infrequent cause of neonatal infection, but is associated with a high degree of morbidity and mortality. We postulate that this neonate acquired P. shigelloides via the transplacental route, and suggest that this organism be included in the list of 'other' causes of transplacental infection that has been abbreviated to 'O' in the acronym 'TORCH'.

Animals↗
PubMed1997

Simple choristoma of the anterior segment containing brain tissue.

We report an unusual case of a simple choristoma of the anterior segment that contained only brain tissue. The clinical characteristics and findings of pathological examination of this unusual ocular malformation were reviewed. A newborn girl was seen with a fleshy, highly vascular cystic mass arising from the inferior limbus and extending across the cornea. On a computed tomographic scan, gross disruption of the anterior segment was present, with subluxation of the lens into the cyst. Excision of the abnormal tissue was followed by evisceration; polyglactin (Vicryl) ball implantation; patch graft of the globe; and, later, prosthetic fitting. Pathologic findings showed a choristomatous malformation, containing only mature brain tissue. To our knowledge, a choristoma in which the sole constituent is brain tissue has not previously been reported.

Anterior Eye Segment↗
PubMed1996

The importance of injection rate in achieving a single intraocular gas bubble.

We investigated factors involved in achieving a single gas bubble following intravitreal gas injection during surgery for retinal detachment. A simple mathematical model of gas bubble dynamics within the eye was developed. The model indicates that the speed at which the bubble rises within the eye is proportional to the radius of the bubble. The flow rate required to maintain a single bubble increases as a power function of the bubble radius. In conclusion, the speed of injection is of paramount importance in the attainment of a single gas bubble.

Dilatation↗
PubMed1996

Visually impaired children with sensory defect nystagmus, normal appearing fundi and normal ERGS.

The differentiation of congenital motor nystagmus (CMN) from sensory defect nystagmus (SDN) in early life is a common diagnostic problem, since their wave forms are indistinguishable. A diagnosis of SDN is made when fundal or ERG abnormalities are present. CMN is generally diagnosed by exclusion. This approach can lead to late or incorrect diagnosis, and to the overlooking of important genetic implications. In addition, the classification of congenital nystagmus into pure motor and sensory types is inadequate. The authors present case reports illustrating this problem and suggest strict criteria for a diagnosis of CMN. They also point out that a miscellaneous group of rare disorders of the macula tend to be overlooked and misdiagnosed.

Adolescent↗
PubMed1995

Retinal detachment and giant retinal tears in aniridia.

Clinical findings in aniridia may include corneal epitheliopathy, glaucoma, lens subluxation and cataract, and hypoplasia of the fovea and optic nerve. We report the occurrence of retinal detachment due to giant tears in four eyes of three children with aniridia. All eyes were buphthalmic and none had undergone lens or posterior segment surgery. All operated eyes underwent vitreolensectomy and silicone oil injection; useful vision was restored in two eyes. The pathogenesis and management of this previously unreported complication are discussed.

Aniridia↗
PubMed1994

Granular corneal dystrophy. Visual results and pattern of recurrence after lamellar or penetrating keratoplasty.

BACKGROUND: Granular corneal dystrophy is a rare indication for corneal transplantation. Both penetrating and lamellar keratoplasty have been recommended, but because granular corneal dystrophy is known to recur within the donor material and multiple grafts may be necessary, the best surgical option has not been clearly established. The cellular cause of the dystrophy is unknown and the authors hypothesized that the rate and pattern of recurrence within lamellar and penetrating grafts might give clues to its etiology. METHODS: The authors compared the visual outcome, rate, and pattern of recurrence after 20 penetrating keratoplasties and 11 lamellar keratoplasties for granular corneal dystrophy. RESULTS: Penetrating keratoplasty and lamellar keratoplasty have a good visual outcome in granular corneal dystrophy. Visual acuities after both procedures were not statistically different. Recurrence of the dystrophy within the graft material was almost universal within 4 years. It first appeared centrally and superficially, occasionally adopting a vortex pattern suggesting epithelial involvement. The recurrence-free interval was independent of size and type of graft performed. CONCLUSION: The authors recommend lamellar keratoplasty as a primary procedure in managing visually disabling granular corneal dystrophy if the deposits are limited to the superficial cornea. This is particularly applicable in younger patients in whom multiple procedures may be necessary over a lifetime due to recurrence of the dystrophy, and the lower morbidity rate associated with lamellar keratoplasty becomes appreciable. Although granular corneal dystrophy generally is classified as a stromal dystrophy, the pattern of recurrence is more consistent with an epithelial or tear-borne abnormality than a disease of the stromal keratocyte.

Adolescent↗